1. Field of the Invention
The present invention generally relates to a heat dissipation device for removing heat from a heat-generating device, and more particularly to a heat dissipation device with heat pipes for cooling an electronic device such as a Central Processing Unit (CPU).
2. Description of Related Art
Electronic devices such as central processing units (CPUs) generate lots of heat during normal operation. Unless removed, such heat will adversely affect the operational stability of the CPUs. Solutions must be taken to efficiently remove the heat. Typically, a heat sink is mounted on a CPU to remove heat therefrom.
Conventional heat sinks such as aluminum extrusion type heat sinks are widely used for heat dissipation of electronic devices. However, the aluminum extrusion type heat sinks which each commonly include a flat base and a plurality of fins extending integratedly from the base, have many disadvantages. The first is that the total surface area of the fins available for heat dissipation is very limited as the distance between adjacent fins cannot be desirably small enough. This seriously bars improvement of the heat removal rate of the aluminum extrusion type heat sinks. Another disadvantage is that the heat generated by heat sources cannot be rapidly transferred to remote portions of the fins so that the remote portions have a relatively lower heat dissipation effect. This also limits heat dissipation efficiency of the heat sinks.
To solve the above disadvantages of aluminum extrusion type heat sinks, a heat sink having an inverted-T-shaped base and a plurality of fins, has been developed. Taiwan Patent Issue No. 326939 shows an example of this kind of heat sink. The performance of this kind of heat sink is greater than aforesaid aluminum extrusion type heat sinks. However, heat is transferred to the fins still by a conventional conduction which is inherently slow and not enough to remove the heat promptly from the heat source to meet the requirement of heat dissipation of high-powered heat-generating electronic devices.
To enhance the performance of a heat sink, nowadays, heat pipes have been widely used. A heat pipe is a pipe with a hermetically sealed chamber, in which a wicking structure is formed and working fluid is filled. The heat pipes work as follows. Thermal energy enters an evaporating section of the heat pipe and vaporizes the working fluid. The working fluid moves in the heat pipe to an area of lower temperature, and then condenses. After the vapor condenses, the wicking structure draws the liquid back to the evaporating section by capillary action of the wick structure. The cycle is repeated continuously and heat is transferred from high temperature area to low temperature area. Because of the rapid transport capability of the vapor, the heat pipe has a very highly effective thermal conductivity over a long distance. In order to improve performance of a heat sink, today heat pipes are widely used in combination with the heat sink. The combination manner between the heat pipes and the heat sink significantly affects heat dissipation effectiveness of a heat dissipation device consisting of the heat sink and the heat pipes.
Therefore, it is desired to design a novel heat dissipation device with heat pipes wherein the heat pipes are combined with a heat sink in such a way that the heat dissipation device can have an optimal heat dissipation effect.